BOB.1 (SP92)

Expression of BOB.1/OBF.1 is restricted largely to mature B-cells. Germinal center B-cells normally demonstrate strong staining for BOB.1, as do mantle-zone B-cells, and plasma cells.1,2 Analyses of BOB.1/OBF.1 expression in a variety of established B-cell lines representing different stages of B-cell development has suggested a constitutive, B-cell-specific expression pattern. Because they are germinal center derived, L&H cells in nodular lymphocyte predominant Hodgkin lymphoma are consistenty immunoreactive for BOB.1. Conversely, the Hodgkin/Reed-Sternberg cells in classical Hodgkin lymphoma either do not express both (80%) or express only one (20%) of the two proteins.2-6 In B-cell lymphomas, the highest expression levels for BOB.1/OBF.1 are reported in follicular center lymphomas7,8, diffuse large B-cell lymphomas9,10, and Burkitt lymphomas10. B-CLL, MALT-type, and mantle cell lymphomas score negative or display an heterogenous/weaker reactivity.10-11 Studies have suggested that anti-BOB.1 has a high predictive value in discriminating primary mediastinal B-cell lymphoma from classical Hodgkin disease.12,13 Approximately 50% of acute myeloid leukemias express BOB.1. 14